[Scip] Deleting variables

[Jonas Witt]

Hi Gerald,

thanks, it worked.

Best regards,
Jonas

Am 23.04.2013 11:04, schrieb Gerald Gamrath:
> Hi Jonas,
>
> please add an if( prob->transformed ) before the call of
> SCIPprobUpdateNObjVars(). This methods updates the counter for the
> number of variables with nonzero objective coefficient, but this counter
> is only used in the transformed problem.
>
> Best,
> Gerald
>
>
> On 23.04.2013 10:48, Jonas Witt wrote:
>> Hi Timo, Ambros and Gerald,
>>
>> I already called  SCIPfreeTransform() and the deleted flag of
>> SCIPdelVar() returns TRUE.
>>
>> I added the line
>> SCIP_CALL( SCIPprobPerformVarDeletions(scip->origprob,
>> scip->mem->probmem, scip->set, scip->stat, scip->eventqueue, scip->lp,
>> scip->branchcand) );
>> but then I got the following:
>>
>> gcg.linux.x86_64.gnu.dbg.spx: src/scip/prob.c:1480:
>> SCIPprobUpdateNObjVars: Assertion `prob->transformed' failed.
>>
>> Program received signal SIGABRT, Aborted.
>> 0x00007ffff6b78425 in __GI_raise (sig=<optimized out>) at
>> ../nptl/sysdeps/unix/sysv/linux/raise.c:64
>> 64    ../nptl/sysdeps/unix/sysv/linux/raise.c: Datei oder Verzeichnis
>> nicht gefunden.
>> (gdb) bt
>> #0  0x00007ffff6b78425 in __GI_raise (sig=<optimized out>) at
>> ../nptl/sysdeps/unix/sysv/linux/raise.c:64
>> #1  0x00007ffff6b7bb8b in __GI_abort () at abort.c:91
>> #2  0x00007ffff6b710ee in __assert_fail_base (fmt=<optimized out>,
>> assertion=0xc54a71 "prob->transformed", file=0xc53ce0 "src/scip/prob.c",
>>       line=<optimized out>, function=<optimized out>) at assert.c:94
>> #3  0x00007ffff6b71192 in __GI___assert_fail (assertion=0xc54a71
>> "prob->transformed", file=0xc53ce0 "src/scip/prob.c", line=1480,
>>       function=0xc55080 "SCIPprobUpdateNObjVars") at assert.c:103
>> #4  0x000000000081b044 in SCIPprobUpdateNObjVars (prob=0x252a3d0,
>> set=0x23bb720, oldobj=0, newobj=0) at src/scip/prob.c:1480
>> #5  0x0000000000819e24 in SCIPprobPerformVarDeletions (prob=0x252a3d0,
>> blkmem=0x23b9700, set=0x23bb720, stat=0x2529970, eventqueue=0x0,
>>       lp=0x0, branchcand=0x0) at src/scip/prob.c:1066
>> #6  0x00000000008402dc in SCIPdelVar (scip=0x23b6770, var=0x6dd6498,
>> deleted=0x7fffffffba00) at src/scip/scip.c:8958
>>
>> Thanks for your help and best regards,
>> Jonas
>>
>>
>> Am 23.04.2013 10:28, schrieb Gerald Gamrath:
>>> Hi all,
>>>
>>> I guess it is not fixed by calling SCIPfreeTranform(), because he wants
>>> to delete original variables. With SCIPdelVar(), these variables are
>>> marked for deletion, but the final deletion is never performed for the
>>> original problem. We could think of adding an interface method that can
>>> be used to trigger the deletion. For now, I would suggest the following:
>>> In SCIPdelVar(), in case SCIP_STAGE_PROBLEM, please add the line
>>> SCIP_CALL( SCIPprobPerformVarDeletions(scip->origprob,
>>> scip->mem->probmem, scip->set, scip->stat, scip->eventqueue, scip->lp,
>>> scip->branchcand) );
>>> after the SCIPprobDelVar() call. Then, the marked variable should be
>>> deleted immediately.
>>>
>>> Best,
>>> Gerald
>>>
>>> On 23.04.2013 09:54, Ambros Gleixner wrote:
>>>> Hi Jonas,
>>>>
>>>> deleting variables is only difficult during the solution process.  As I
>>>> understand, you want to delete variables only after finishing one solve.
>>>>     To do this, you have to call SCIPfreeTransform() to return to the
>>>> problem creation stage.  Does this solve your problem?
>>>>
>>>> Best regards,
>>>>
>>>> Ambros
>>>>
>>>>
>>>> Am 23.04.2013 08:53, schrieb Jonas Witt:
>>>>> Hi all,
>>>>>
>>>>> I'm having problems with deleting variables. I know you list deleting
>>>>> variables as a known bug on your website, but maybe you can still help me.
>>>>>
>>>>> I use a sub-SCIP and initialize it with some initial variables and
>>>>> constraints. This should work as some kind of pattern. So everytime I
>>>>> use this sub-SCIP, I want to add new variables and constraints to it,
>>>>> solve it and then delete the recently added variables and constraints.
>>>>> So after this solving proccess, the sub-SCIP should only consist of
>>>>> initial variables and constraints.
>>>>>
>>>>> I delete the recently added constraints with SCIPdelCons(). After this
>>>>> deletion the recently added variables do not belong to any constraint of
>>>>> the problem. Then I tried to delete these variables via SCIPdelVar() but
>>>>> failed (the variables still belong to the problem). It is important to
>>>>> really delete these variables and not just fix them to zero.
>>>>>
>>>>> How can I use the sub-SCIP the way I have described it without copying
>>>>> the whole problem?
>>>>>
>>>>> Best regards,
>>>>> Jonas
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